The present invention relates to a CATV (cable television or community antenna television) system.
In CATV systems, a center facility provides own programs and commercial broadcast programs on the air to a plurality of subscriber terminal apparatuses via transmission cables. In recent years, services of CATV systems include data transmission. Further, bi-directional CATV systems are now operated in which each terminal apparatus can transmit a signal (i.e., an up signal) to a center facility. CATV systems limitedly operated in schools, hotels, etc. are specifically called "CCTV (closed circuit television) system."
In the conventional CATV systems, to select a desired program to see it on a TV receiver, a user needs to refer to a program table that is distributed in advance, find a channel of the desired program, and operate a channel selection switch of a controller to set his terminal apparatus to that channel. To make the TV receiver display a certain message transmitted from the center facility, all the message data are stored in a buffer memory of the terminal apparatus. The message data read from the buffer memory are provided to a character generator, and an output of the character generator is superimposed on a video signal.
In the above CATV systems, the center facility is required to prepare a program table and distribute its copies in advance, and to broadcast programs in accordance with the program table thus prepared. However, the preparation of program tables needs some cost, and the flexibility of program organization is reduced, for instance, the programs cannot be altered once the program table is prepared. On the other hand, on the terminal apparatus side, a user cannot know without referring to the program table whether a desired program is scheduled to be broadcast. In addition, a procedure of program selection is complex.
Further, in the above conventional CATV systems, because the number of broadcast channels is insufficient, it is a general procedure that the same chargeable program is rebroadcast in unfixed time periods rather than, for instance, every 30 minutes. Therefore, when a viewer previously stopped watching a certain program in the midst of its broadcast and wants to see in another time the remaining a part of the same program that he failed to see, he needs to wait for the next rebroadcast or to record that program by a VCR etc. by checking in advance the start time of the next rebroadcast. However, a cumbersome procedure is required to see the rebroadcast program, or such an attempt sometimes results in a failure.
Further, the above conventional CATV systems employ a charging system in which a viewer is charged for chargeable programs on a program-by-program basis, as this system is called PPV (pay per view). In this system, a viewer is charged a full charge even if he has ordered a program in the midst of its broadcast. Since viewing of a certain program can be ordered any time during its broadcast, a viewer is charged a full charge even if he has ordered it only a short time before the end of the program.